An adjusting device for a deflection fitting of a vehicle safety belt system conventionally comprises a rail which is secured to the vehicle and is provided with catch openings, and a slider able to be slid in the rail, such slider being provided for mounting the deflection fitting and possessing a detent mechanism adapted to cooperate with the catch openings.
Such an adjusting device serves to adapt the way in which the safety belt is spread out to suit the vehicle occupant in the best possible manner. Problems may occur when using such an adjusting device, if the slider is located between two catch openings just when an accident happens, that is to say it is not anchored as required at a catch opening. Such problem is made even more acute if the safety belt system is provided with a belt pretensioner, which in an accident takes up slack in the safety belt system. The forces acting on the deflection fitting may prevent the detent mechanism from satisfactorily snapping into the next catch opening so that the slider is displaced downward in relation to the vehicle and consequently the action of the belt pretensioner is impaired as well. Therefore detent mechanisms have been proposed designed to ensure reliable snapping into the next following catch opening even if the slider is under extremely high downward acceleration in relation to the vehicle. However, with such an improved detent mechanism the action of the belt pretensioner is impaired by there being a certain distance to be moved through by the slider before the detent mechanism fits into the next following catch opening.